1. Technical Field
The present invention relates to a vehicle seat belt retractor having a comfort mechanism. In particular, the present invention relates to a release mechanism for deactuating the comfort mechanism.
2. Description of the Prior Art
Seat belt retractors having comfort mechanisms for relieving the force applied by seat belt webbing against a vehicle occupant are known. One such seat belt retractor is disclosed in U.S. Patent No. 4,002,311 and includes seat belt webbing secured to a spindle. The spindle is supported for rotation in belt withdrawal and belt retraction directions. A spring biases the spindle to rotate in the belt retraction direction and pulls the seat belt webbing against the occupant. To relieve the force applied by the belt webbing against the occupant, the occupant establishes slack in the belt webbing and actuates the comfort mechanism to maintain the slack.
The comfort mechanism includes a disk connected to the spindle for rotation with the retractor spindle. A groove having a stop surface is located in an axial end surface of the disk. When the comfort mechanism is actuated, an end portion of a follower engages the stop surface, and blocks rotation of the disk and spindle in the belt retraction direction.
A release mechanism moves the follower out of engagement with the stop surface on the disk to deactuate the comfort mechanism in response to opening of the vehicle door. The comfort mechanism may also be deactuated by withdrawing more than a predetermined amount of belt webbing from the retractor. When more than the predetermined amount of belt webbing is withdrawn, the follower is forced out of the groove in the disk to a position in which the follower no longer engages the stop surface and the comfort mechanism is deactuated. In certain cases, the amount of seat belt webbing which is withdrawn when full extension of the seat belt webbing is reached may be less than the predetermined amount of belt webbing and the comfort mechanism does not deactuate. Thus, it is necessary to open the vehicle door to deactuate the comfort mechanism. Opening the vehicle door may be undesirable, however.
A release mechanism disclosed in U.S. Pat No. 4,149,683 deactuates a comfort mechanism similar to the comfort mechanism of U.S. Pat. No. 4,002,311 in response to full extension of the seat belt webbing. Thus, the above-mentioned problem with the comfort mechanism release of U.S. Pat. No. 4,002,311 is avoided. In U.S. Pat. No. 4,149,683, the seat belt webbing has an end portion looped around the retractor spindle and stitched to another portion of the seat belt webbing. An end surface of the seat belt webbing extends perpendicular to the direction in which the webbing is withdrawn. The end surface of the webbing engages a lever just prior to full extension of the webbing from the spindle. The lever has a portion which engages the follower of the comfort mechanism. As the seat belt webbing is then withdrawn to full extension, the lever is moved by the end surface of the webbing in the direction of belt withdrawal. During movement of the lever, the follower is forced into a position in which the follower does not engage the stop surface on the disk. This deactuates the comfort mechanism.